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Association Between Nursing Home Crowding and COVID-19 Infection and Mortality in Ontario, Canada

Educational Objective
To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  What is the association of crowding in nursing homes, defined as the mean number of residents per bedroom and bathroom, with nursing home coronavirus disease 2019 (COVID-19) mortality?

Findings  In this cohort study that included more than 78 000 residents of 618 nursing homes in Ontario, Canada, COVID-19 mortality in homes with low crowding was less than half (578 of 46 028 residents [1.3%]) than that of homes with high crowding (874 of 32 579 residents [2.7%]).

Meaning  Shared bedrooms and bathrooms in nursing homes are associated with larger and deadlier COVID-19 outbreaks.


Importance  Nursing home residents have been disproportionately affected by coronavirus disease 2019 (COVID-19). Prevention recommendations emphasize frequent testing of health care personnel and residents, but additional strategies are needed.

Objective  To develop a reproducible index of nursing home crowding and determine whether crowding was associated with COVID-19 cases and mortality in the first months of the COVID-19 epidemic.

Design, Setting, and Participants  This population-based retrospective cohort study included more than 78 000 residents across more than 600 nursing homes in Ontario, Canada, and was conducted from March 29 to May 20, 2020.

Exposures  The nursing home crowding index equaled the mean number of residents per bedroom and bathroom.

Main Outcomes and Measures  The cumulative incidence of COVID-19 cases confirmed by a validated nucleic acid amplification assay and mortality per 100 residents; the introduction of COVID-19 into a home (≥1 resident case) was a negative tracer.

Results  Of 623 homes in Ontario, we obtained complete information on 618 homes (99%) housing 78 607 residents (women, 54 160 [68.9%]; age ≥85 years, 42 919 [54.6%]). A total of 5218 residents (6.6%) developed COVID-19 infection, and 1452 (1.8%) died of COVID-19 infection as of May 20, 2020. COVID-19 infection was distributed unevenly across nursing homes; 4496 infections (86%) occurred in 63 homes (10%). The crowding index ranged across homes from 1.3 (mainly single-occupancy rooms) to 4.0 (exclusively quadruple occupancy rooms); 308 homes (50%) had a high crowding index (≥2). Incidence in high crowding index homes was 9.7% vs 4.5% in low crowding index homes (P < .001), while COVID-19 mortality was 2.7% vs 1.3%, respectively (P < .001). The likelihood of COVID-19 introduction did not differ (high = 31.3% vs low = 30.2%; P = .79). After adjustment for regional, nursing home, and resident covariates, the crowding index remained associated with an increased incidence of infection (relative risk [RR] = 1.73, 95% CI, 1.10-2.72) and mortality (RR, 1.69; 95% CI, 0.99-2.87). A propensity score analysis yielded similar conclusions for infection (RR, 2.09; 95% CI, 1.30-3.38) and mortality (RR, 1.83; 95% CI, 1.09-3.08). Simulations suggested that converting all 4-bed rooms to 2-bed rooms would have averted 998 COVID-19 cases (19.1%) and 263 deaths (18.1%).

Conclusions and Relevance  In this cohort of Canadian nursing homes, crowding was common and crowded homes were more likely to experience larger and deadlier COVID-19 outbreaks.

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Article Information

Accepted for Publication: September 18, 2020.

Published Online: November 9, 2020. doi:10.1001/jamainternmed.2020.6466

Corresponding Authors: Kevin A. Brown, PhD, Dalla Lana School of Public Health, University of Toronto, 480 University Ave, Ste 300, Toronto, ON M5G1V2, Canada (; and Nathan M. Stall, MD, Division of General Internal Medicine and Geriatrics, Mount Sinai Hospital, 600 University Ave, Ste 475, Toronto ON M5G 2C4 Canada (

Author Contributions: Dr Brown had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Brown, Jones, Garber, Costa, Stall.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Brown, Jones.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Brown, Jones.

Obtained funding: Costa.

Administrative, technical, or material support: Brown, Schwartz, Garber, Costa.

Supervision: Brown, Garber, Costa.

Conflict of Interest Disclosures: Dr Stall is supported by the Department of Medicine’s Eliot Phillipson Clinician-Scientist Training Program and the Clinician Investigator Program at the University of Toronto and the Vanier Canada Graduate Scholarship. Dr Costa holds the Schlegel Chair in Clinical Epidemiology and Aging at McMaster University. Dr Brown reported a familial tie with an employee of an architecture firm that has consulted on projects for implementing physical distancing in shelter systems. No other disclosures were reported.

Additional Contributions: We acknowledge the support of Michael Hillmer, PhD, Kamil Malikov, MBA, MD, and Sping Wang, PhD, Ontario Ministry of Health Capacity Planning and Analytics Division, for assistance with data acquisition, interpretation, and analysis. No compensation was received for their contributions.

Yourish  K , Lai  KKR , Ivory  D , Smith  M . One-third of all U.S. coronavirus deaths are nursing home residents or workers. Accessed June 6, 2020.
Hsu  AT , Lane  N , Sinha  SK ,  et al.  Impact of COVID-19 on Residents of Canada’s Long-Term Care Homes—Ongoing Challenges and Policy Responses. International Long-Term Care Policy Network; 2020.
Fisman  DN , Bogoch  I , Lapointe-Shaw  L , McCready  J , Tuite  AR .  Risk factors associated with mortality among residents with coronavirus disease 2019 (COVID-19) in long-term care facilities in Ontario, Canada.   JAMA Netw Open. 2020;3(7):e2015957. doi:10.1001/jamanetworkopen.2020.15957PubMedGoogle Scholar
Verity  R , Okell  LC , Dorigatti  I ,  et al.  Estimates of the severity of coronavirus disease 2019: a model-based analysis.   Lancet Infect Dis. 2020;20(6):669-677. doi:10.1016/S1473-3099(20)30243-7PubMedGoogle ScholarCrossref
Guan  WJ , Liang  WH , Zhao  Y ,  et al; China Medical Treatment Expert Group for COVID-19.  Comorbidity and its impact on 1590 patients with COVID-19 in China: a nationwide analysis.   Eur Respir J. 2020;55(5):2000547. doi:10.1183/13993003.00547-2020PubMedGoogle Scholar
CDC COVID-19 Response Team.  Preliminary estimates of the prevalence of selected underlying health conditions among patients with coronavirus disease 2019—United States, February 12-March 28, 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(13):382-386. doi:10.15585/mmwr.mm6913e2PubMedGoogle ScholarCrossref
Drinka  PJ , Krause  P , Schilling  M , Miller  BA , Shult  P , Gravenstein  S .  Report of an outbreak: nursing home architecture and influenza-A attack rates.   J Am Geriatr Soc. 1996;44(8):910-913. doi:10.1111/j.1532-5415.1996.tb01859.xPubMedGoogle ScholarCrossref
Ryan  A , Lazar  K . A new analysis: coronavirus death rate surged in Massachusetts locations that already faced challenges. Accessed June 9, 2020.
Emeruwa  UN , Ona  S , Shaman  JL ,  et al.  Associations between built environment, neighborhood socioeconomic status, and SARS-CoV-2 infection among pregnant women in New York City.   JAMA. 2020;324(4):390-392. doi:10.1001/jama.2020.11370PubMedGoogle ScholarCrossref
Stall  NM , Jones  A , Brown  KA , Rochon  PA , Costa  AP .  For-profit long-term care homes and the risk of COVID-19 outbreaks and resident deaths.   CMAJ. 2020;192(33):E946-E955. doi:10.1503/cmaj.201197PubMedGoogle ScholarCrossref
Long-Term Care Facility Design Manual. Ministry of Health and long-term care. Accessed June 12, 2020.
Advantage Ontario. About long term care homes. Accessed August 3, 2020.
Statistics Canada. Population projections for Canada (2018 to 2068), provinces and territories (2018 to 2043). Accessed June 18, 2020.
Ministry of Health. Case definition—COVID-19. Accessed September 17, 2020.
Lipsitch  M , Tchetgen Tchetgen  E , Cohen  T .  Negative controls: a tool for detecting confounding and bias in observational studies.   Epidemiology. 2010;21(3):383-388. doi:10.1097/EDE.0b013e3181d61eebPubMedGoogle ScholarCrossref
Ministry of Health and Long-Term Care. Long-term care home design manual 2015. Accessed June 12, 2020.
Mor  V .  A comprehensive clinical assessment tool to inform policy and practice: applications of the minimum data set.   Med Care. 2004;42(4)(suppl):III50-III59. doi:10.1097/01.mlr.0000120104.01232.5ePubMedGoogle Scholar
Austin  PC , Merlo  J .  Intermediate and advanced topics in multilevel logistic regression analysis.   Stat Med. 2017;36(20):3257-3277. doi:10.1002/sim.7336PubMedGoogle ScholarCrossref
Haukoos  JS , Lewis  RJ .  The propensity score.   JAMA. 2015;314(15):1637-1638. doi:10.1001/jama.2015.13480PubMedGoogle ScholarCrossref
Austin  PC .  An introduction to propensity score methods for reducing the effects of confounding in observational studies.   Multivariate Behav Res. 2011;46(3):399-424. doi:10.1080/00273171.2011.568786PubMedGoogle ScholarCrossref
Poole  C .  A history of the population attributable fraction and related measures.   Ann Epidemiol. 2015;25(3):147-154. doi:10.1016/j.annepidem.2014.11.015PubMedGoogle ScholarCrossref
Calkins  M , Cassella  C .  Exploring the cost and value of private versus shared bedrooms in nursing homes.   Gerontologist. 2007;47(2):169-183. doi:10.1093/geront/47.2.169PubMedGoogle ScholarCrossref
Kane  RA , Baker  MO , Salmon  J , Veazie  W . Consumer perspectives on private versus shared accommodations in assisted living settings. Accessed June 21, 2020.
Nichols  J.   Private rooms not always a better place for residents.   Caring for the Ages. 2014;15(2):3. doi:10.1016/j.carage.2014.01.004Google ScholarCrossref
Stiller  A , Salm  F , Bischoff  P , Gastmeier  P .  Relationship between hospital ward design and healthcare-associated infection rates: a systematic review and meta-analysis.   Antimicrob Resist Infect Control. 2016;5(1):51. doi:10.1186/s13756-016-0152-1PubMedGoogle ScholarCrossref
King  M-F , Noakes  CJ , Sleigh  PA , Camargo-Valero  MA .  Bioaerosol deposition in single and two-bed hospital rooms: a numerical and experimental study.   Building and Environment. 2013;59:436-447. doi:10.1016/j.buildenv.2012.09.011Google ScholarCrossref
MacIntyre  CR , Kendig  N , Kummer  L , Birago  S , Graham  NMH .  Impact of tuberculosis control measures and crowding on the incidence of tuberculous infection in Maryland prisons.   Clin Infect Dis. 1997;24(6):1060-1067. doi:10.1086/513632PubMedGoogle ScholarCrossref
Langford  BJ , Daneman  N , Leung  V ,  et al  The second-hand effects of antibiotics: communicating the public health risks of drug resistance.   JAC-Antimicrobial Resistance. 2019;1(3):dlz059. doi:10.1093/jacamr/dlz059Google Scholar
Brown  KA , Jones  M , Daneman  N ,  et al.  Importation, antibiotics, and Clostridium difficile infection in veteran long-term care: a multilevel case-control study.   Ann Intern Med. 2016;164(12):787-794. doi:10.7326/M15-1754PubMedGoogle ScholarCrossref
US Centers for Disease Control and Prevention. Preparing for COVID-19 in nursing homes. Accessed June 13, 2020.
Gaur  S , Dumyati  G , Nace  DA , Jump  RLP .  Unprecedented solutions for extraordinary times: helping long-term care settings deal with the COVID-19 pandemic.   Infect Control Hosp Epidemiol. 2020;41(6):729-730. doi:10.1017/ice.2020.98PubMedGoogle ScholarCrossref
World Health Organization.  Preventing and Managing COVID-19 across Long-Term Care Services: Policy Brief. World Health Organization; 2020.
Grant  K , Ha  TT . How shoring up hospitals for COVID-19 contributed to Canada’s long-term care crisis. Accessed June 6, 2020.
Culhane  D , Treglia  D , Steif  K , Kuhn  R , Byrne  T . Estimated emergency bed need for the US homeless population related to COVID-19 exposure. Accessed June 8, 2020.
Ministry of Health and Long-Term Care. COVID-19 directive #3 for long-term care homes under the Long-Term Care Homes Act. Accessed June 6, 2020.
Chen  S , Zhang  Z , Yang  J ,  et al.  Fangcang shelter hospitals: a novel concept for responding to public health emergencies.   Lancet. 2020;395(10232):1305-1314. doi:10.1016/S0140-6736(20)30744-3PubMedGoogle ScholarCrossref
Kenette  W. When a gym becomes a home: Highlighting the need for long-term care reform. Accessed July 27, 2020.
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